How to create expandable panels using swing?

You can take a look to JXTaskPaneContainer and JXTaskPane from SwingX project which have these advantages:

• They are components just like a JPanel is so no extra effort is required to work with them.
• Unlike accordions you can have more than one panel expanded at any time.
• They have a cool and smooth effect on collapsing/expanding events.
• Unlike trees/tree tables you don't have to mess with either TreeModel nor TreeTableModel at all. Also trees and tree tables are components intended to show data in a hierarhical form, not to add components into it.

If you don't like task panes and want to implement something on your own then you have JXCollapsiblePane (also available in SwingX API).

Check SwingLabs Demos for a complete set of SwingX components demo.

Screenshot

Look at JXTreeTable from the SwingX project:

You might also look at JXTree, which is similar, and might be better, depending your exact needs.

Get it from here.

The component you're looking for is an accordion. Have a look at this question: Accordion for Swing?

As to your code - you can only see the last one because you're adding them all to a panel with a BorderLayout, with BorderLayout.North as the layout constraint. Each one removes the previously added panel. Try switching to another layout - e.g. BoxLayout.